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Hi,
I power the Seq v4 with USB , Fine , stable (since a month)
i want to permute for a permanent dedicated PSU than USB in the seq case  (BLM extension ready)
so i've bought a meanwell 5V 3A at reichelt .

Meanwell PSU

this switching PSU made the Control Surface crash! ( i suspect interaction between supply switching frequency and the frequency of the CS matrix also ripple/noise)
i could build filters to sleek the PSU but the config is a bit special. (filter have to be well designed for a certain current, BLM is not constent current, and if the CS crash the BLM will do too! don't like this sensible way)

so i thinking use classic design PSU with transformer and a linear LT1085-5 regulator (not done yet)
i never used this regulator but i will test.

Is someone have experience , suggestion or tips with higher current than 7805 regulator. (perhaps another regulator familly than LT1085)
Thanks
Nico

 

Edited by tashikoma
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Hi Nico,

do you have an oscilloscope at hand for measuring the ripple?

Without big filtering calculation you could try a 2200uF and a 47uF cap pair in parallel, sometimes it might already help.

I use an open-frame psu from reichelt, too, for powering the SEQ, and there are no problems, but have no BLM installed.

Inexpensive "UBEC"-type low-noise switching regulators from the model plane sector are an additional option: I use a common 12V unregulated wallwart and one of these to power the MBProgramma with 24 OLEDs and 1024 LEDs :

http://rctimer.com/product-160.html

:-)

Many greets,

Peter

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Hi Peter,
You're right , i test with a scope and the Meanwell PSU is linear. no ripple. ( the switching frequency interaction problem seems to be a complot theory from my imagination!:grin:)
today the SEQ is stable (4h running)  with the meanwell no CS crash... i don't understand , no change have be made ... i don't know what happens yesterday! (it was a rainy day)
yesterday i flip several times between USB and  Meanwell PSU and the bug was reccurrent with the Meanwell. (power at J2 withouth the USB power jumper)
i will do tests next days and run the SEQ to see if crash reapear...

you're "UBEC" regulator from modelism is a great tip, i will give it a try... thanks

Best
Nico
 

 

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Hi Nico,

you're welcome - maybe there is some solder residual somewhere sometimes bridging 5v and ground.
And you are right, when there are strange hardware or software problems, I also always blame the weather! Hehehe! :-)

Have a great weekend!

Bye,

Peter

 

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that sounds weird, check the voltage when powered up.  Switching supplies have load requirements so going too low can cause problems.  For the one I just built, I used a 5V 2.5A wallwart that I cannibalized for an old USB hub, should be plenty.  My seq draws all of 300 mA and that's with IIC, Midi I/O and port extender

 

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Hm, looks noisy - we don't know the scope y-axis resolution, but anyways, but that noise might very well be the problem!

It might be coupled with Altitudes minimum-current requirement observation, because the ripple may be more prominent, if not enough current is drawn.

How long is the wire from the switcher to the core?

Can you insert a cheap LC filter at the core end? Things necessary to build it:

one big cap (2200uF)

one small cap (100nF - 47uF)

one ferrite core with at least three windings of the plus side of the cable through it.

This should filter out the worst stuff - here is a DIY instruction:

http://blog.oscarliang.net/lc-filter-fpv/

just add the small cap in parallel to the big cap, this further improves filtering performance. These filters have helped me a lot in other (non-music) applications, they really work and only cost a few cents and half an hour to try out. If you are interested, you can re-measure with your scope after installing the filter - should be lots better! :-)

Many greets,

Peter

 

Edited by Hawkeye
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I found a few (old, like 25 y/o VSOP!) "Eurorack" PSUs. Not in the modular synth style but built for DIN rail electronics. They offer 5V 3A and +/-12V 0.3A. It's a linear design with a large transformer and heat sink, but uses LM723 as a precision rectifier and driver transistors to boost the current. I should really replace the old caps but at the moment it's running the SEQ and BLM just fine.

Model is TRACOPOWER TCP531

 

Edited by latigid on
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Yeah Andrew! TRACOPOWER  with symetrical 12V is good for CV outputs....:grin:

after do more tests ( was busy this week)
I found that the random noise in the video is from an ethernet powerline device . not from the supply or seq! (mesured at 50mV (100mV P-P)):decayed:

10 cm between core and PSU.

internal ripple of the seq is consequent with the meanwell! 30mV (60mV P-P)


Peter your filter rocks!:love:
attenuation of 30mV ripple to 5mV (10 mV P-P) and good sleekage. with the scope and filter it's ok!

but without the scope and with the filter the CS crash immediatly after power on!
i see the real benefit of the filter and hazard made the filter permit me to "force" bug! (extra cap of 2200uF will act as reserve of power)

the seq current is 270 mA , without (for the moment) the IIC and midi indicator external leds.

i test with USB powa' or classic transfomer/7805 and lab PSU and the seq is stable....

The crash is caused by low load of switching PSU , the PSU go to "idle" mode! (5.050v to 4.930v)...
Have to do tests with more load on the PSU... perhaps  a regulator or UBEC to load the switching PSU would do the trick!

Or SEQ with extra external ledstripes!:itsok:

The simplest way is to go with classic design PSU and leave the idea of powering BLM from SEQ... from this switching PSU.
a supply for BLM another one for SEQ and one for the line driver CV rack! there will be for everyone:happy:
also it's a bad idea to have long extension of power rail with high current low voltage...
 

IMG_77531.jpg

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Hey, well built! :-)

And glad you made some more important observations! You can re-use that LC-filter also in other projects, and as it seems, Altitude was right -> not enough current draw for the switcher :). More LEDs is always a good thing! ;-)

Have a great weekend!

Peter

 

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  • 2 weeks later...

Good news:happy:
it's a rainy day! so recidivism to crazy experimentation on the meanwell:decayed:

with IIC midi and line driver transmitter the SEQ draw 300mA , line driver seems to stabilise the PSU load!
with IIC midi ,ethernet module and line driver transmitter, the SEQ draw 410mA ...
when line driver transmitter is in communication the current rise at 600mA (i don't test with ethernet communication but seems to be +100mA)
the CS is now stable! the PSU works perfectly!!!!
also stable with the LC-filter. (who previously force to bug)

on the meanwell datasheet this PSU seems to be capable from 0 to 3A:disgusted: no load requirement! but reality says more than 300mA to work!
i keep the meanwell in the case, the SEQ is now BLM powering ready:love:
youpi!
morality : at 10e it's a good value if more 300 mA load is respected:angelnot:

thanks Peter ,Altitude & Andy!

Edited by tashikoma
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:grin: Sounds good! Thanks for sharing your research data regarding power consumption of the SEQ and especially the minimum current requirements for one of those meanwell switching PSUs!

Have a great weekend!

Peter

 

Edited by Hawkeye
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